The present invention relates generally to a power plug receivable within a lighter socket of a motor vehicle for connecting an electrically powered device to the electrical system of the motor vehicle, and more particularly, to such a power plug which includes at least one securing pad mounted thereon for frictionally engaging the lighter socket to resist movement of the power plug within the socket. The present invention is particularly applicable for powering radar detectors and accordingly will be described with reference to this application.
Radar warning detectors are known in the prior art. Such detectors comprise a police radar warning receiver which is mountable in a vehicle, such as a car, truck, boat, or the like, which travels in areas subject to speed-monitoring radar surveillance by police. The warning receiver functions to detect the presence of police radar and provides the driver or user with an audible and/or visual indication that his speed is being checked by radar. Typically, the receiver comprises operating circuitry and an antenna, which are mounted within a box-shaped housing positionable on the dashboard of a vehicle. The front of the housing faces the driver and has indicators and control knobs. Extending from the housing is a power cord terminating in a power plug which is appropriately configured to be received within the vehicle's lighter socket. The power plug connects electrical energy from the vehicle's electrical system to the receiver via the power cord.
Prior art power plugs comprise a plastic housing having a forward tubular end which is shaped to be slidably received within a vehicle's lighter socket. Typically positioned opposite the tubular end of the housing is a gripping end sized to be gripped between the user's fingers and thumb for insertion and removal of the plug from the lighter socket. Commonly mounted in the distal end of the forward tubular end of the housing is a contact which provides an electrical connection with the vehicle's electrical system (normally, the positive supply line or the positive terminal of the vehicle battery). Also mounted in the forward tubular end of the housing and extending therefrom are metallic spring arms which provide an electrical connection with the vehicle's electrical system (normally, the vehicle ground). The spring arms further serve to releasably retain the tubular end of the housing within the lighter socket.
It has been found that these prior art power plugs have a tendency to move out of a vehicle's lighter socket due to vibrations generated by the vehicle. Accordingly, there is a need for an improved power plug which can be readily inserted into and removed from the lighter socket of a motor vehicle yet is reliably retained within the lighter socket.